Compression refrigerating system for low temperature purposes



May 21, 1935. HQIBRIER ET AL COMPRESSION REFRIGERATING SYSTEM FOR LOW TEMPERATURE PURPOSES Filled Nov. 10, 19:52

Patented May 21, 1935 UNITED STATES PATENT OFFICE COMPBESSION narnrosaa'rmo 'SYSTEM .roa LOW 'rnmrsaa'ruas rrmrosns Henry Brlerand John Iiornsby Brier,

. Dartford, England 3 Claims.

- vention is also concerned with the production of dry ice or CO: snow. I

Broadly the invention consists in providing low temperature cooling by employing'pre-cooiing of the vapour or gas from a primary evaporator or pre-cooler as part of a three stage compression in one cylinder in such manner as to obtain the greatest volume of the gas or vapour from the primary evaporator in the first stage of compression.

In the operation of the refrigerating system of the invention the refrigerant such as CO: or any other suitable refrigerant after compression into an ordinary condenser is first expanded or partially evaporated and pre-cooled thereby into a primary evaporator, such as is in common use, in which the liquid is separated from the vapour.

The pre-cooled liquid portion is then allowed to pass into the evaporator, where it expands doing useful cooling work. thevapour thus formed being drawn into one end of a compressor cylinder. This charge is supplemented by the vapour portion separated from the liquid CO: or other refrigerant in the primary evaporator as a second charge at higher pressure which is delivered to the same side of the piston through a suction valve provided for the purpose or through ports in the walls of the cylinder uncovered by the piston at the extreme end of its suction stroke. The initial charge from the evaporatoris thereby compressed to the higher pressure ruling in the primary evaporator and this constitutes the first stage of compression.

0n the return stroke of the piston the combined charges are compressed by way of a cooler, if suitable or required, into the other end of the cylinder, which has a suitably smaller volumeth is constitutes the second stage of compression-and on the next stroke are then compressed in a third or final stage compression into the condenser.

In the application of the invention to the production of dry ice or C0: snow, 00: from a suitable source such as a CO: producer is subjected to three-stage compression in a cylinder such as above described, the charge of the cylinder being supplemented as before from a primary evaporator. The liquid portion from the prim ry evaporator is, however, delivered'to an evaporation or snow box for the production of ice-or CO: snow. This'snow box may be .in communication by way of a non-return valve with the conduit through which the CO: from the producer or the like is drawn into the compressor cylinder.

A compression refrigerating system forming the subject of the invention is illustrated diagrammatically in Fig. l of the accompanying 5 drawing. Fig. 2 illustrates also diagrammatically the application of the invention to the productionof dry ice or CO2 snow.

Referring to Fig. l, A denotes generally a compressor used as a three stage compressor, B a condenser, C a primary evaporator and liquid regulator and D an evaporator. E denotes the piston. The full line position of the piston indicates its position at the end of the suction stroke and first compression stroke at one end and the third compression stroke at the other end The dotted line position corresponds to the position of the piston at the end of its second compression stroke.

The refrigerant such as CO: is compressed by means of the piston E in its outward stroke through the outlet valve G into the condenser B and thence is passed through the regulator valve H into a primary evaporator C with a liquid regulator shown as being of the type described in our prior U. S. Patent specification No. 1,452,999. In this primary evaporator C the liquid is separated from the vapour, the liquid being passed through the pipe I to the evaporator D, where it does useful cooling work, the vapour thereby formed being drawn through the inlet valve K into the one end of the cylinder by the piston E on its outward stroke. The vapour from the primary evaporator C is passed as a second charge at higher pressure through a separate valve or through the ports L in the wall of the compressor behind the piston E '35 and thus.to the same side of the piston, as the ports L are uncovered by the piston at the extreme end of its suction stroke. The initial charge passed from the evaporator through the inlet valve K is thereby compressed to the higher pressure ruling in the primary evaporator and consti tutes a first stage of compression.

- On the return stroke of the piston the combined charges are passed through the outlet'valve M and the conduit N and inlet valve 0 into the front end of the cylinder which is smaller by the dimensions of the piston rod. and this constitutes the second stage of compression. It will be seen that on the return stroke of the piston the ports L are not uncovered by the ,piston rod end: of the piston. A

'cooler (not shown) may be interposedin the con duit N. On the next outward or suction stroke of the piston E these gases are compressed in a third or final stage into the condenser B. It will be clear that since the first compression is efl'ected without a compression stroke of the piston three compressions are performed by two strokes of the piston or one revolution of the crank shaft.

It is of course obvious that while the above description refers to the use of a single cylinder, a number of similar cylinders may be used in a freezing system embodying the invention.

In the application of the invention to the making of dry ice or CO: snow, in lieu of the evaporator D a snow or ice making vessel or chamber of any suitable description will be provided for the reception of the liquid contents of the primary evaporator C, and CO: from a suitablesource such as a CO: producerwill be drawn into the compressor cylinder. The charge drawn in will be supplemented as above described from the primary evaporator. The other stages of compression will be carried out as before. The snow or ice making vessel may be connected through a. non-return valve with the conduit supplying the CO2 to the compressor cylinder from the CO: producer so that the CO: vapour from the snow box may be used to supplement that coming from the producer.

We claim:-

1. The improvement in the compression-refrigerating method of attaining unusually low temperatures by a refrigerant, comprising first subjecting the refrigerant to a primary evaporation to pre-cool same, then drawing the working gas or vapor from the main evaporator into a single container and adding the gaseous refrigerant from i the primary evaporator, and efiecting a first stage compression of the working gas from the main evaporator in the single container, thus raising.

2. In a compression-refrigerating system of the kind involving pre-cooling of the refrigerant by primary evaporation, a primary-evaporator, a compressor having a piston, means for delivering the gas or vapor from the main evaporator thereto on its suction stroke, and for raising the pressure on this side of the piston by the gas from the primary evaporator, and adding same to the contents of the compressor at the end of its suction stroke, a conduit for connecting opposite ends of the cylinder of the compressor whereby to deliver the gases to the front end of the cylinder and compress them further by virtue of the capacity in either end of the cylinder being different, a condenser, and means for compressing said gases in a third compression into said condenser on the return stroke of the piston.

3. In a compression-refrigerating system of the kind involving pre-cooling of the refrigerant by primary evaporation, a primary evaporator, a compressor having a piston, means for delivering the gas or vapor from the main evaporator thereto on its suction stroke, and for raising the pressure on this side of the piston by the gas from the primary evaporator, same being'added to the contents of the compressor at the end of its suction stroke, a conduit for connecting opposite ends of the cylinder of the compressor whereby to deliver the gases to the front end of the cylinder and compress them further by virtue of the capacity in either end of the cylinder being different, a condenser, and means for compressing said gases in a third compression into said condenser on the return stroke of the piston, the compressor being formed with openings adapted to be uncovered by the piston on its first-stage suction stroke, said openings being in communication with the said gas conduit leading from the primary evaporator.

HENRY BRIER. JOHN HORNSBY BRIER.

CERTIFICATE OF CORRECTION.

Patent No. 2,002,307. May 21, 1935.

HENRY BRIER. ET AL.

'It is hereby certified that error appears in the printed specification of .the above numbered patent requiring correction as follows: Page 1, first column, line 2, for "systems" read machines; line 4-5, for the period and words The invention is also concerned with" read or for; line 8, for "of" read and employing;.and lines l1, l2 and 13, strike out the words "obtain the greatest volume of the gas or vapour from the primary evaporator in" and insert the word constitute; page 2, first column, line ll, afterjhefl syllable "her" insert the letter and number P (Fig.2); line 20, after "valve" insert 0; and line 23, after "box" insert P; and that the said Letters Patent should be read with these corrections therein that the same may conform to the record of the case in the Patent Office. I

' Signed and sealed this 16th day of July, A. D. 1935.

(Seal) Acting fibhhhi fo ri r of Patents 

